Focus: A point under the surface of the Earth, where the rock that s under stress breaks, starting an Earthquake. Epicenter: A point on the surface of earth, exactly above the focus. Seismic waves: The viabration that goes through earth holding the energy that has been let go during an earthquake. P waves: Waves from an earthquake that squeeze or stretch the ground. S waves: Waves from an earthquake that shake from one side to another, or in an up-or-down motion. Surface waves: Waves from an earthquake that can make the most dangerous ground movements. Seismograph: A device that copies the vibrations that come from seismic waves, as they go through earth. Magnitude: An instrument that measures the movement of seismic waves. Mercalli Scale: Estimates earthquakes, based on their energy they create. Richter Scale: Estimates that size of a seismic wave, using a kind of seismograph Moment Magnitude Scale: Estimates earthquake of all sizes, wherever they are.
Outline
Seismic Waves
Seismic Waves are like ripples that travel through water, except underground
waves travel from the focus, through earth, and to the epicenter.
Primary Waves (P waves)
First waves to arrive, compress and expand ground like accordion.
Go up and down, side to side, violently shake buildings
Secondary Waves (S waves)
After P waves, can't go through liquid (kind of wavy)
Go up and down, side to side,violently shake buildings
Surface Waves
When P and S reach surface, they create surface waves
Slower than P and S, but make severest ground movements
Detecting Seismic Waves
Use seismographs:pen writes on roll of paper and moves more when the ground moves more (mechanical)
Electronic seismographs record and can also print
Measuring Earthquakes
The Mercalli Scale
rates according to intensity and damage; has 12 steps
The Richter Scale
Rating of size of seismic waves, not good for big earthquakes
The Moment Magnitude Scale
modern; used to measure quakes of all sizes
Created with the electronic seismograph
Locating The Epicenter
Scientists look at the seismograph data from different areas and create data from different areas and create at least three wave circles.
They then find the center of those circles:the epicenter.
Table of Contents
2.2 Measuring Earthquakes
Vocabulary
Focus: A point under the surface of the Earth, where the rock that s under stress breaks, starting an Earthquake.
Epicenter: A point on the surface of earth, exactly above the focus.
Seismic waves: The viabration that goes through earth holding the energy that has been let go during an earthquake.
P waves: Waves from an earthquake that squeeze or stretch the ground.
S waves: Waves from an earthquake that shake from one side to another, or in an up-or-down motion.
Surface waves: Waves from an earthquake that can make the most dangerous ground movements.
Seismograph: A device that copies the vibrations that come from seismic waves, as they go through earth.
Magnitude: An instrument that measures the movement of seismic waves.
Mercalli Scale: Estimates earthquakes, based on their energy they create.
Richter Scale: Estimates that size of a seismic wave, using a kind of seismograph
Moment Magnitude Scale: Estimates earthquake of all sizes, wherever they are.
Outline
Seismic Waves
- Seismic Waves are like ripples that travel through water, except underground
- waves travel from the focus, through earth, and to the epicenter.
Primary Waves (P waves)- First waves to arrive, compress and expand ground like accordion.
- Go up and down, side to side, violently shake buildings
Secondary Waves (S waves)Surface Waves
Detecting Seismic Waves
Measuring Earthquakes
The Mercalli Scale- rates according to intensity and damage; has 12 steps
The Richter Scale- Rating of size of seismic waves, not good for big earthquakes
The Moment Magnitude ScaleLocating The Epicenter
- Scientists look at the seismograph data from different areas and create data from different areas and create at least three wave circles.
- They then find the center of those circles:the epicenter.
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